A capillary electrophoresis device is widely used as a device for analyzing nucleic acids, proteins or the like. The capillary electrophoresis device is a device that analyzes a sample in the following manner. Specifically, an electrophoresis medium (a separation medium) such as a polymer gel or a polymer solution is filled into a narrow tube called a capillary, and a high voltage is applied thereto. The sample is analyzed by utilizing an electrophoresis mobility difference caused by a molecular size difference.
The capillary electrophoresis device mainly includes: a capillary; a power source configured to apply a high voltage between ends of the capillary; an irradiation system configured to emit laser light onto an inspection region; a photoreceptor optical system configured to detect fluorescence generated due to the irradiation of the laser light; a temperature conditioning unit configured to control the temperature of the capillary; a filling unit configured to fill the electrophoresis medium into the capillary; and the like.
Meanwhile, the filling unit needs to inject an electrophoresis medium having a viscosity several hundred times higher than that of water into a capillary having an inner diameter of approximately 50 μm. Thus, the filling unit is required to be capable of generating a pressure of even several mega Pascals. For this reason, a plunger pump is used for the filling unit, for example.
In addition, the capillary electrophoresis device applies a high voltage of several to tens of kilovolts to the capillary during electrophoresis. Thus, if bubbles are present in a flow passage of the electrophoresis medium, the flow passage is electrically blocked in some cases. In such cases, a high voltage is generated in the electrophoresis medium blocked by the bubbles and thus might cause a discharge phenomenon. The discharge sometimes destroys the device. For this reason, the bubbles need to be removed from the flow passage of the electrophoresis medium before the electrophoresis is started.